| 摘要 |
<p>PROBLEM TO BE SOLVED: To accurately control a frequency to both high frequency side and low frequency side, and to enable frequency control even after outer packaging. SOLUTION: In a process S6, the oscillation frequency of an oscillator is measured. When the oscillation frequency is deviated to the low frequency side, in a process S9, a DC voltage is impressed between the external electrodes of the oscillator and an electric field in the same direction as in the polarizing direction of a piezoelectric substrate is generated between vibrating electrodes. Thus, the polarization degree of the piezoelectric substrate in an area held between the confronted vibrating electrodes is improved, and the oscillation frequency of the oscillator is increased. Conversely, when the oscillation frequency is deviated to the high frequency side, in a process S10, an electric field opposite to the polarizing direction of the piezoelectric substrate is generated between the vibrating electrodes.</p> |
